Fluid mechanics and Mechanical operations quiz 2019

FLUID MECHANICS AND MECHANICAL OPERATIONS QUIZ

Q. 1 The liquid flow rate through an equal percentage control valve, when fully open, is 150 gal/min and the corresponding pressure drop is 50 psi. If the specific gravity of the liquid is 0.8, then the valve coefficient,C_v in gal/( min psi^0.5) is.........(rounded off to two decimal places).

Q. 2.Consider a cylinder (diameter D and length D), a sphere (diameter D) and a cube (side length D). Which of the following statements concerning the sphericity φ of the above objects is true:

φ_sphere > φ_cylinder > φ_cube
φ_sphere = φ_cylinder = φ_cube
φ_sphere < φ_cylinder φ_cube
φ_sphere > φ_cylinder = φ_cube

Q. 3 For a fully-developed turbulent hydrodynamic boundary layer for flow past a flat plate, the thickness of the boundary layer increases with distance x from the leading edge of the plate, along the free-stream flow direction, as

x^0.5
x^1.5
x^0.4
x^0.8

Q. 4 A centrifugal pump is used to pump water (density 1000 kg / m³ ) from an inlet pressure of 10⁵ Pa to an exit pressure of 2 * 10⁵ Pa. The exit is at an elevation of 10 m above the pump. The average velocity of the fluid is 10 m/s. The cross-sectional area of the pipes at the pump inlet and outlet is 10^-3 m² and acceleration due to gravity is g = 10 m/ s². Neglecting losses in the system, the power (in Watts) delivered by the pump is..............(rounded off to the nearest integer)..

Q. 5 For a hydraulic lift with dimensions shown in figure, assuming g = 10 m/ s² , the maximum diameter D_kft(in m) that lifts a vehicle of mass 1000 kg using a force of 100 N is ...........(rounded off to two decimal places).

Q. 6 A disk turbine is used to stir a liquid in a baffled tank. To design the agitator, experiments are performed in a lab-scale model with a turbine diameter of 0.05 m and a turbine impeller speed of 600 rpm. The liquid viscosity is 0.001 Pa s while the liquid density is 1000 kg / m³ . The actual application has a turbine diameter of 0.5m, an impeller speed of 600 rpm, a liquid viscosity' of 0.1 Pa s and a liquid density of 1000 kg / m³ . The effect of gravity is negligible. If the power required in the lab-scale model is P₁ and the estimated power for the actual application is P₂ then the ratio P₂ / P₁ is

10³
10⁴
10⁵
10⁶

Q. 7 An incompressible Newtonian fluid flows in a pipe of diameter D₁ at volumetric flow rate Q. Fluid with same properties flows in another pipe of diameter D₂ = D₂ / 2 at the same flow rate Q. The transition length required for achieving fully-developed flow is l₁ for the tube of diameter D₁ , while it is l₂ for the tube of diameter D₂. Assuming steady laminar flow in both cases, the ratio l₁ / l₂ is:

1/4
1
2
4